This application relates to electronic signaling and, more particularly, to driving a visual status indicator array in an electronic signaling system, such as those found in network repeaters and switches.
Many computer networks rely on network repeaters and switches to facilitate the exchange of information among the computers in the network. In many networks, such as Ethernet networks, information is exchanged in the form of data packets that pass through each of the repeaters or switches in the network. The repeaters or switches usually monitor the data packets to collect information on the status of network resources. Network administrators then use the status information to manage the network resources.
One way of conveying the status information from a repeater to a network administrator is through visual indicators, such as an array of light emitting diodes (LEDs). In many cases, each LED in the array is dedicated to presenting information about a particular status condition on a particular repeater port. The network administrator can determine whether a particular status condition exists on a repeater port by observing whether the corresponding LED in the array is illuminated. One problem with this technique is that additional pins must be added to the repeater chip to deliver status signals to the LED array, thus driving up the cost and complexity of the repeater chip.
Sophisticated techniques have been developed to reduce the number of signal lines required to drive an LED indicator array in a network repeater. In one such technique, a 16xc3x975 array of LEDs provides information about five status conditions for each of sixteen repeater ports. The LED array is driven by eight time-multiplexed signals, each of which carries information about all five status conditions for two of the sixteen repeater ports. While this technique for driving the LED array succeeds in placing a great deal of information on very few status lines, the technique requires a relatively sophisticated multiplexing circuit in the repeater chip and an equally sophisticated demultiplexing scheme at the LED array. This technique is much more suited for use with large LED arrays than it is for small arrays, such as a 4xc3x974 or a 6xc3x973 array.